The present invention relates to conductive compositions for use in connection with electronic systems and, in particular, the use of such compositions to provide continuous designs on a variety of objects.
Conductive compositions have been developed for various purposes including facilitating electrostatic discharge and as a current transfer medium on printed circuit boards. Conductive compositions have also been used, instead of conventional conductive wires, as a means for conducting current from a power source to one or more current operated modules on a variety of objects such as wearing apparel, toys posters, books and numerous other electronic devices.
U.S. Pat. No. 5,455,749 to Ferber (“the '749 patent”), owned by the assignee of the present invention and which is incorporated by reference herein in its entirety, discloses examples of desirable electrical systems that use conductive compositions. The '749 patent discloses electrical systems which include a power supply, one or more current operated modules and conductive compositions for use in connecting the power supply to a current operated module. In one embodiment of the '749 patent, the conductive composition may be colored and may form at least a portion of a design on the surface of a substrate.
U.S. Pat. No. 5,626,948 to Ferber et al. (“the '948 patent”), which is also owned by the assignee of the present invention and which is incorporated by reference herein in its entirety, discloses an electrical system having a multi-layer conductive composition. In accordance with the '948 patent, when pressure is applied to the top layer composition, a closed circuit condition occurs causing current to flow from the second layer composition vertically up through the top layer composition.
U.S. Pat. No. 5,973,420 to Kaiserman et al. (“the '420 patent”), which is also owned by the assignee of the present invention and which is incorporated herein by reference in its entirety, discloses an electrical system having a clear conductive composition. In accordance with the '420 patent, a clear conductive composition is arranged on a substrate and provides an electrical circuit path between a power source and a responsive circuit element. A trigger point is included within the circuit path by providing an open circuit area in the clear conductive composition. Upon placement of a conductive object across the open circuit area a closed circuit condition is created whereby current flows to the responsive circuit element.
In some applications it is desirable to mask the open circuit area from the user. For example, where conductive compositions are used to provide a design on a sheet that is meant to be colored by a child, if the child is able to immediately recognize the open circuit area the child may more easily focus on closing the circuit instead of coloring the design. In addition, where the electrical circuit path forms, for example, circuitry for a light switch or alarm system, a user may want to mask the location of the open circuit area for security reasons. Of utility then are methods and systems that can mask open circuit areas that are formed on circuit paths or make such open circuit areas appear as integral parts of the circuit path.